Field of the Invention
The present invention relates to a method for automated process control in a digital printing machine system by using a computer.
The technical field of the invention is the field of digital printing.
Setting up, calibrating and operating a complex machine system such as that of a digital printing machine, in particular an inkjet printing machine, requires a plurality of parameters to be considered. The prior art includes various approaches to this process of efficiently setting up a printing machine, for instance in terms of preparing for a new print job. Those approaches substantially include the implementation of manual process control, caused and initiated by a human operator, and/or a default implementation of process control before the start of every print job. In that process, some or all of the required setting parameters and influencing parameters of the digital printing machine are checked and potentially necessary steps, for instance recalibration steps, are taken to correct the relevant parameters. However, those different approaches are dependent on the knowledge and experience of the human operator and are frequently very inefficient as a consequence. The default implementation of process control for every new print job is very complex and time-consuming. Another disadvantage is that in some cases it may not be necessary at all. That presents a massive potential for improvement.
A known improved process control approach for digital production printing is known as the Barbieri DOC solution which discloses such process control developed by the Barbieri Company. In that process, a mobile measuring device is used to examine the print result in terms of the achieved color fidelity. Using that mobile measuring device at regular intervals thus allows an ongoing printing process to be monitored in terms of whether the color output continues to be within predefined tolerances. If that is not the case, a suitable warning is generated and output to the operator of the printing machine, giving the operator the opportunity to counteract the defect by recalibrating the machine in a suitable way and/or by modifying other settings of the printing machine. Nevertheless, a disadvantage of that process is that it is the development of only one parameter of the printing machine system, namely color fidelity—albeit a very important parameter—that is continuously monitored. Other important parameters such as the operating time that has elapsed since the last calibration of the printing machine system or the printing speed, etc. are not taken into consideration.
Another approach, known from U.S. Pat. No. 8,711,380, is to implement an automated printing machine system calibration process based on the contents of the print jobs pending on the printing machine system to be controlled. That document discloses carrying out an automated assessment of print job data or image data present in the print job data for potentially useful information in terms of the calibration of the printing machine. In that process, the image data of the pending print job/s is/are analyzed, namely in the context of influencing parameters of a print model, in order to achieve improved print quality by using that print model. The data that have been analyzed in that way refer to information about the start-up of the printing machine, the operation, and maintenance cycles in terms of the current print job in question. Nevertheless, a disadvantage of that approach is that only data that are related to the current print job are examined whereas general information and statuses of the printing machine system are not taken into closer consideration. The printer output, i.e. the quality of the print results of the printing machine, is also not included in the analysis for process control purposes.